81816544 has 24 divisors (see below), whose sum is σ = 162018360. Its totient is φ = 40669056.

The previous prime is 81816499. The next prime is 81816557. The reversal of 81816544 is 44561818.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1854 + ... + 12925.

It is an arithmetic number, because the mean of its divisors is an integer number (6750765).

Almost surely, 2^81816544 is an apocalyptic number.

It is an amenable number.

81816544 is a deficient number, since it is larger than the sum of its proper divisors (80201816).

81816544 is a wasteful number, since it uses less digits than its factorization.

81816544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14962 (or 14954 counting only the distinct ones).

The product of its digits is 30720, while the sum is 37.

The square root of 81816544 is about 9045.2498030734. The cubic root of 81816544 is about 434.1239143009.

The spelling of 81816544 in words is "eighty-one million, eight hundred sixteen thousand, five hundred forty-four".